Does Effluent Water Affect the Ecosystem in Fountain Hills, Arizona?

Fountain Hills Fountain and park

On my way to school each day in my hometown of Fountain Hills, Arizona, I pass the Fountain Hills Fountain and park. The park, built in 1970, includes 35 acres of turf and a 33-acre, million-gallon effluent lake. Effluent water is recycled wastewater, used to fill the lake and water the park. The fountain draws water from the lake and erupts up to 560 feet when all three pumps are running. During the course of a year I have observed that the area goes through cycles. At times the lake is full of animal and plant life, and other times the water is gloomy, looking as if nothing could survive. I wondered, Why does the town use effluent water in a public area? I decided to investigate.

Domesticated mallards and American coots in the lake

Journal Entry: November 6, 2004, 1 p.m. Today I went to the park and surveyed the area. I had with me my field journal, camera, binoculars, map of the park, and traveling pack. The water was quite clear, with mallard ducks, domesticated mallards, and American coots swimming in it. No fish were observed in this lake water. I noticed that there were fewer animals on the southwestern side of the water, where most of the ducks lingered on the green grass eating "treats" thrown by visitors. All of the other areas of the lake had ducks in the water.

I returned home and began researching books and articles about the history of the lake and effluent water. In order to conserve our diminishing supply, the use of water has been reduced to 10% fresh water and 90% effluent water to irrigate turf in the state of Arizona.

Journal Entry: November 9, 2004 Today I met with the district engineer, Michael S. Thompson, and engineering technician, Robert Howes, of the Chaparral City Water Company (CCWC). It is the freshwater headquarters to both Fountain Hills and Scottsdale, Arizona. They gave me a tour of the freshwater facilities and explained the process of the water treatment. Surface water from Lake Pleasant and the Colorado River is combined with ground water from alluvial aquifers below the city of Fountain Hills. The fresh water, after treatment, is pumped into homes and commercial and industrial businesses. I now have a better understanding of the town's freshwater source, but my question is, does the use of effluent water affect the ecosystem?

Journal Entry: November 17, 2004 Today I met with the plant operations manager, Clark Moskop, of the Fountain Hill's Sanitary District. Visitors from different countries, such as China and Germany, come to this plant to observe how to treat water. Here, I learned about the water flowing in for treatment through both gravity and pumping stations.

Pipes leading to an aeration basin

Schematic drawing of water treatment process (Click to enlarge)

The water is treated by an aerobic, or oxygen-rich, procedure in which chemicals such as magnesium hydroxide Mg(OH)2, which neutralizes acids; chlorine (Cl), for disinfection; and polymers, substances consisting of giant molecules that help the solids stay together, are used. As I walked through the plant, I heard loud clanking sounds coming from the main processor, or screen, through which the "raw"effluent water flows. It removes foreign objects from the water and disposes of them. From the screen, I followed a pipe that extended to an aeration basin underneath the ground. Here, microorganisms such as stalked ciliates consume the organic matter. This mixture of microorganisms and raw effluent is known as "mixed liquor."

I wondered how the microorganisms could stay alive in this sealed environment. A pipe pumps oxygenated air into the basin where the microorganisms absorb organic matter through their cell membranes and digest it to carry on their life process. Looking into the basin, I saw the brown tint of the sludge washing up the concrete walls, extending into the darkness.

Disinfection tanks

After the aeration basin is a secondary clarifier, or settling tank, where the microorganisms settle out. The microorganisms, now referred to as "sludge," are recycled to the aeration basin to maintain the process. Mr. Moskop then led me to a large, spacious building containing blue cylinders, about six feet long, that were making a faint swishing noise. The liquids from the clarifier are transported here for disinfection and final discharge.

Journal Entry: December 21, 2004, 10:45 a.m. Today I returned to the park. It was an overcast day. I took two samples from the eastern and southwestern sides of the lake. The temperature of the water was 50° F. I noticed once again that more animal life was in the teal-colored water on the eastern side, whereas only four American coots swam on the southwestern side. All the other mallard ducks and American coots wandered in the grass. I took the samples home for testing and further research. I plan to go at a later date and collect more.

Christina taking a water sample

The first sample I took was on the eastern side of the lake, near an input pipe from which effluent water flowed into the lake. Using a microscope, I identified crawling ciliates and free-swimming ciliates, which feed on individual bacteria cells and seed shrimp. I also located an ostracod, which feeds on small plankton. The water also contained some bacteria and lots of closteriopsis algae. Using pH test strips, I found the pH level to be 9.05.

The second sample, taken on the southwestern side, contained many more microorganisms than the first. Through the microscope I saw something that looked like a tulip and identified it as a stalked ciliate, which feeds on individual bacteria cells. To the left of the stalked ciliate was a bdelloid rotifer, which feeds on small plankton. There were also two carnivorous ciliates, which feed on other protozoa. To my surprise, I found a worm in the closteriopsis algae. On this sample, the pH level was 8.34.

This research made me more interested in my subject, as I saw that there were more microorganisms on the southwestern side of the lake, which the animals seemed to avoid. I postulated that the difference in the amount and types of microorganisms is due to the constant influx of effluent water on the eastern side of the lake. I decided to examine a freshwater source, Saguaro Lake, a recreation and tourist area located northeast of Fountain Hills.

Journal Entry: December 27, 2004, 10 a.m. I have just taken four samples from Saguaro Lake, where the water temperature was 55° F. Many visitors were out in the clear water with boats. I collected one sample from the north and the northeastern sides of the lake, and two from the southeastern. In the shallows there were crawfish and many small fish, such as minnows and sunfish. The water here was clear and light blue, with mallards, golden eyes, and bufflehead ducks swimming and a great blue heron off to the side of the lake.

Journal Entry: December 27, 2004, 11 a.m. I took one more sample from the Fountain Hills Lake on the northern side. Here, the ducks stayed in the water and did not venture out onto the grass. I went back to the southwestern side and took one last sample. This time the animals had spread out to other parts of the lake, leaving this side vacant. I left Fountain Park to test the waters from both lakes.

The first sample from Saguaro Lake contained free-swimming ciliates, many flagellated protozoa, scenedesmus and closteriopsis algae, and a pH of 8.18. The second sample had many flagellated protozoa and closteriopsis algae, and a pH of 7.94. The third had two gastrotrich, flagellated protozoa, and scenedesmus algae, with a pH of 8.05. The last sample contained many free-swimming ciliates and closteriopsis algae, with a pH of 8.10.

Chart of microorganisms found in Fountain Lake (Click to enlarge)

I tested the southwestern sample of the Fountain Lake and found some scenedesmus and closteriopsis algae, as well as many free-swimming ciliates, stalked ciliates, and bdelloid rotifers, and a pH of 9.06. The northern side contained some free-swimming ciliates, stalked ciliates, and many ankistrodesmus and oscillatoria algae, with a pH of 8.94.

Conclusion I started with the question, Does effluent water affect the ecosystem in Fountain Hills, Arizona? The pH in Saguaro Lake runs between 7.9 and 8.2. The pH in Fountain Hills Lake runs between 8.9 and 9.05. This is probably due to the phosphates and detergents in the effluent water. Saguaro Lake is a freshwater lake and Fountain Hills Lake is an effluent lake. There are more microorganisms in Fountain Hills Lake than in Saguaro Lake. In addition, I have observed that there are algal blooms in Fountain Hills Lake that do not occur in Saguaro Lake. The algal blooms produce a distasteful odor that I did not observe at Saguaro Lake.

Chart of study data (Click to enlarge)

Admittedly, Fountain Hills is a closed lake, with water loss due only to evaporation, while Saguaro Lake drains into the Salt River, in a more natural process. However, it does appear that more microorganisms inhabit Fountain Hills Lake than Saguaro Lake. Around the input pipe for the effluent water, the pH is an extreme 9.05, and waterfowl appeared to avoid this area.

My conclusion is that effluent water does impact the ecosystem negatively. Although the use of effluent water conserves fresh water, the effluent lake is not as healthy as a natural lake. Arizona is in its ninth year of a drought, and water conservation is a priority. However, effluent water does not produce as good an environment as using fresh water would.